Optical Signal Routing Devices and Systems

ABSTRACT

One example LIDAR device comprises a substrate and a waveguide disposed on the substrate. A first section of the waveguide extends lengthwise on the substrate in a first direction. A second section of the waveguide extends lengthwise on the substrate in a second direction different than the first direction. A third section of the waveguide extends lengthwise on the substrate in a third direction different than the second direction. The second section extends lengthwise between the first section and the second section. The LIDAR device also comprises a light emitter configured to emit light. The waveguide is configured to guide the light inside the first section toward the second section, inside the second section toward the third section, and inside the third section away from the second section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/835,464, filed Jun. 8, 2022, which is a continuation of U.S. patentapplication Ser. No. 16/667,833, filed Oct. 29, 2019. The foregoingapplications are incorporated herein by reference.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Optical waveguides can be used in a variety of systems, such as medicaldevices, manufacturing systems, and remote sensing devices (e.g.,LIDARs, etc.), among other examples. In general, an optical waveguide isa device that defines an optical path for guiding an optical signal fromone spatial position (where the signal enters the waveguide) to anotherspatial position (where the signal exits the waveguide). In one example,an optical waveguide may include an optical material having a higherrefractive index relative to its surrounding medium. Due to thedifference between the refractive indexes, light propagating inside theoptical material (or portions thereof) may reflect at one or more wallsof the optical material back into the optical material (e.g., totalinternal reflection (TIR)) and then continue propagating inside theoptical material. Thus, depending on a shape and/or other physicalproperties of the optical material, the optical waveguide may define aspecific optical path for optical signals guided therein.

SUMMARY

In one example, a light detection and ranging (LIDAR) device comprises asubstrate and a waveguide disposed on the substrate. A first section ofthe waveguide extends lengthwise on the substrate in a first direction.A second section of the waveguide extends lengthwise on the substrate ina second direction different than the first direction. A third sectionof the waveguide extends lengthwise on the substrate in a thirddirection different than the second direction. The second sectionextends lengthwise between the first section and the second section. TheLIDAR device also comprises a light emitter configured to emit light.The waveguide is configured to guide the light inside the first sectiontoward the second section, inside the second section toward the thirdsection, and inside the third section away from the second section.

In another example, a light detection and ranging (LIDAR) devicecomprises a light emitter configured to emit a light signal. The LIDARdevice is configured to transmit a plurality of light beams in arelative spatial arrangement. The LIDAR device also comprises a firstwaveguide configured to receive a first portion of the light signal andto transmit the first portion out of the first waveguide at a firsttransmit location as a first light beam of the plurality of light beams.A first section of the first waveguide extends lengthwise in a firstdirection. A second section of the first waveguide extends lengthwise ina second direction different than the first direction. A third sectionof the third waveguide extends lengthwise in a third direction differentthan the second direction. The LIDAR device also comprises a secondwaveguide configured to receive a second portion of the light signal andto transmit the second portion out of the second waveguide at a secondtransmit location as a second light beam of the plurality of lightbeams.

In yet another example, a method involves a light emitter emitting lightinto a waveguide. The method also involves guiding, inside a firstsection of the waveguide, the light in a first direction toward a secondsection of the waveguide. The first section extends lengthwise in afirst direction. The method also involves guiding, inside the secondsection, the light in a second direction different than the firstdirection toward a third section of the waveguide. The second sectionextends lengthwise in the second direction. The method also involvesguiding, inside the third section, the light in a third directiondifferent than the second direction. The third section extendslengthwise in the third direction.

In still another example, a system comprises means for a light emitteremitting light into a waveguide. The system also comprises means forguiding, inside a first section of the waveguide, the light in a firstdirection toward a second section of the waveguide. The first sectionextends lengthwise in a first direction. The system also comprises meansfor guiding, inside the second section, the light in a second directiondifferent than the first direction toward a third section of thewaveguide. The second section extends lengthwise in the seconddirection. The system also comprises means for guiding, inside the thirdsection, the light in a third direction different than the seconddirection. The third section extends lengthwise in the third direction.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the figures and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates an optical system, according to example embodiments.

FIG. 1B illustrates a cross-section view of the system of FIG. 1A.

FIG. 1C illustrates another cross-section view of the system of FIG. 1A.

FIG. 2A is a simplified block diagram of a LIDAR device, according toexample embodiments.

FIG. 2B illustrates a perspective view of the LIDAR device of FIG. 2A.

FIG. 3A is an illustration of a system that includes a waveguide,according to example embodiments.

FIG. 3B illustrates a cross-section view of the system of FIG. 3A.

FIG. 4A illustrates a first cross-section view of a system that includesa waveguide assembly, according to example embodiments.

FIG. 4B illustrates a second cross-section view of the system of FIG.4A.

FIG. 4C illustrates a third cross-section view of the system of FIG. 4A.

FIG. 4D illustrates a fourth cross-section view of the system of FIG.4A.

FIG. 5 is a flowchart of a method, according to example embodiments.

DETAILED DESCRIPTION

Any example embodiment or feature described herein is not necessarily tobe construed as preferred or advantageous over other embodiments orfeatures. The example embodiments described herein are not meant to belimiting. It will be readily understood that certain aspects of thedisclosed implementations can be arranged and combined in a wide varietyof different configurations. Furthermore, the particular arrangementsshown in the figures should not be viewed as limiting. It should beunderstood that other implementations might include more or less of eachelement shown in a given figure. In addition, some of the illustratedelements may be combined or omitted. Similarly, an exampleimplementation may include elements that are not illustrated in thefigures.

I. OVERVIEW

Some example optical systems disclosed herein can be employed forrouting one or more optical signals (e.g., signal channels) in one ormore optical paths. One example system includes a waveguide disposed ona substrate to define an optical path on the substrate for routing alight signal from an input location to an output location on thesubstrate. In various examples, the optical path may be configured toaccount for various design and physical considerations, such as spacelimitations on the substrate (e.g., other components may be mounted onthe substrate), the input and output locations, and optical propertiesof the waveguide and the light signal (e.g., the critical angle ofincidence required for TIR of the light signal inside the waveguide),among other considerations.

In one example, the waveguide extends lengthwise from a first end to asecond end opposite the first end; and extends widthwise from a firstwall to a second wall opposite the first wall. Additionally, thewaveguide includes a first section extending lengthwise in a firstdirection and a second section extending lengthwise in a seconddirection different than the first direction. For instance, the firstsection may guide the light signal toward the second section, and thesecond section may then guide the light signal away from the firstsection. In some examples, the waveguide may include more sections,where each section extends lengthwise in a different direction than oneor more other sections adjacent thereto.

Thus, with this arrangement, the waveguide can be shaped to define atleast part of the optical path from the input location to the outputlocation, while accounting for space limitations on the substrate. Forexample, other components (e.g., other waveguides, light emitters,circuitry, etc.) can be mounted between the input location and theoutput location without physically intersecting with the optical pathdefined by the waveguide.

In some examples, the first direction of the first section may be offsetfrom the second direction of the second section by a relatively largeoffset angle (e.g., relative to the critical angle associated with TIR,etc.). In one embodiment, the first direction and the second directionmay be perpendicular or nearly perpendicular to one another (e.g.,offset angle between 80 degrees and 100 degrees, etc.). Other offsetangles are possible.

To facilitate this, some examples herein include optical waveguideconfigurations that account for and/or mitigate potential signal leakageassociated with changes to a guiding direction of a waveguide.

Other aspects, features, implementations, configurations, arrangements,and advantages are possible.

II. EXAMPLE SYSTEMS AND DEVICES

FIG. 1A illustrates an optical system 100, according to exampleembodiments.

As shown, system 100 includes a plurality of substrates 184, 186 in anoverlapping arrangement. It is noted that system 100 is shown to includeonly two overlapping substrates 184 and 186 for convenience indescription. However, in alternate embodiments, system 100 couldalternatively include fewer or more substrates.

In the embodiment shown, overlapping sides (e.g., walls) of substrates184 and 186 are arranged substantially parallel to one another. Inalternate embodiments however, a given substrate could instead be tiltedat an offset angle relative to an adjacent substrate in the overlappingarrangement of substrates.

In some examples, the plurality of substrates of system 100 may bephysically coupled to one another such that adjacent substrates areseparated by at least a given separation distance. For example, system100 may also include one or more spacing structures (not shown), such asball bearings, optical fibers, or any other type of solid spacingstructure, disposed between substrates 184 and 186 to physicallyseparate the two substrates from one another by at least the givenseparation distance. The given separation distance may be any distancedepending on various applications of system 100. In one embodiment, thegiven separation distance may be between 1 millimeter and 100millimeters. Other separation distances are possible.

Substrates 184, 186 may include any substrate suitable for supportingone or more signal routing structures (not shown in FIG. 1A) and/orother components of system 100. In one embodiment, overlapping and/orparallel sides of substrates 184, 186 may be configured as mountingsurfaces on which optical waveguides (not shown in FIG. 1A) and/or othercomponents of system 100 are mounted. In this embodiment, the componentsdisposed on a given mounting surface of a given substrate may correspondto a respective layer in a multi-layer assembly of components in system100.

In some embodiments, substrates 184 and/or 186 are formed from orinclude a transparent or partially transparent material (e.g., glassslide, cover glass, plastic film, etc.), which is at least partiallytransparent to one or more wavelengths of light. For example, wheresystem 100 is employed for routing optical signals in the infraredwavelength range, the material used may be at least partiallytransparent to infrared wavelengths. In various examples, otherwavelengths are possible in addition to or instead of infraredwavelengths.

In alternate embodiments, substrates 184 and/or 186 could instead beformed from or include an opaque material (e.g., a semiconductorsubstrate such as silicon or gallium arsenide, a printed circuit board(PCB) substrate, or any other type of opaque substrate).

FIG. 1B illustrates a cross-section view of system 100. For purposes ofillustration, FIG. 1B shows x-y-z axes, where the y-axis extends throughthe page. As shown, system 100 also includes light emitter 140,waveguides 150, 151, 152, and mirrors 160, 161.

Light emitter 140 may include a laser diode, fiber laser, alight-emitting diode, a laser bar, a nanostack diode bar, a filament, aLIDAR transmitter, or any other light source. In some embodiments,emitter 140 may be implemented as a pulsed laser (as opposed to acontinuous wave laser), allowing for increased peak power whilemaintaining an equivalent continuous power output. Other implementationsare possible.

Waveguides 150, 151, 152 can be formed from a glass substrate (e.g.,glass plate, etc.), a photoresist material (e.g., SU-8, etc.), or anyother material at least partially transparent to one or more wavelengthsof emitted light 104. As shown in FIG. 1B, one or more components (e.g.,waveguide 151) are disposed on a first surface (e.g., side 184 a) ofsubstrate 184 as a first layer of component, and one or more othercomponents (e.g., waveguides 150, 152, emitter 140) are disposed on asecond surface (e.g., side 186 a of substrate 186) as a second layer ofoptical components in the multi-layer system 100. Although not shown, insome examples, system 100 may alternatively or additionally include oneor more layers of components mounted on other surfaces of substrates184, 186 (e.g., sides 184 b, 186 b, etc.).

In some embodiments, waveguides 150, 151, 152 can be disposed onto therespective surfaces of substrates 184, 186 shown via opticallithography. For example, a photosensitive material (e.g., photoresist,etc.) can be disposed on substrates 184, 186, exposed to patternedlight, and then selectively etched to form waveguides 150, 151, 152having the respective shapes and positions shown in FIG. 1B. In thisexample, the photosensitive material may be sensitive to the patternedlight prior to etching and fixing the pattern (e.g., and not sensitiveto guided light 104 after the waveguides 150, 151, 152 are etched,etc.). To that end, the photosensitive material may include SU-8 or anyother photosensitive material. In some examples, the photosensitivematerial could be patterned to form other optical elements, such asinput couplers, output couplers, and/or other optical elements inaddition to or instead of waveguides 150, 151, 152. In someimplementations, waveguides 150, 151, 152 may be configured asmulti-mode waveguides to facilitate total internal reflection of lightsignals guided therein. Other implementations are possible as well.

In the example shown, system 100 is shown to include mirrors 160, 161.Mirrors 160, 161 may be formed from any reflective material that hasreflectivity characteristics suitable for reflecting (at leastpartially) wavelengths of light 104. To that end, a non-exhaustive listof example reflective materials includes gold, aluminum, other metal ormetal oxide, synthetic polymers, hybrid pigments (e.g., fibrous claysand dyes), among other examples. Alternatively or additionally, in someimplementations, mirrors 160, 161 may be formed from one or moredielectric materials. In one implementation, mirror 160 (and/or 161) maybe configured as a dielectric mirror (e.g., Bragg mirror, etc.). Forinstance, the dielectric mirror may be formed from multiple layers ofdielectric material. Each dielectric layer may have respective materialtype and/or thickness characteristics suitable for causing thedielectric mirror to reflect one or more wavelengths of light signal 104incident on the dielectric mirror. Other implementations are possible.

In alternative examples, system 100 could be implemented without mirror160 and/or 161. In a first example, waveguide 150 may be configured tointernally reflect light signal 104 at edge 150 b (e.g., via totalinternal reflection (TIR)) without the presence of mirror 160. In thisexample, edge 150 b can be configured as a TIR mirror by selecting atilting angle between edge 150 b and side 150 c such that guided light104 is incident on edge 150 b from one or more angles-of-incidence thatwould cause light 104 to be internally reflected at edge 150 b towardwaveguide 151. Similarly, in a second example, edge 151 a can beconfigured as a TIR mirror (e.g., edge 151 a could be tilted at asuitable tilting angle for TIR of light signal 104 a incident thereonwithout the presence of mirror 161).

In the example arrangement shown in FIG. 1B, emitter 140 is aligned toemit a first light signal 104 into an “input section” of waveguide 150.The input section of waveguide 150 corresponds to a section of waveguide150 (e.g., side 150 a) through which light signal 104 enters thewaveguide. Further, in this example, waveguide 150 is disposed onsubstrate 186 and shaped to define a first optical path inside waveguide150 for guiding light signal 104 (in the x-direction) toward side 150 bof waveguide 150. As shown, side 150 b is tilted toward substrate 184,and mirror 160 is disposed on the tilted edge defined at side 150 b. Inthis example, mirror 160 may be configured as an “output mirror” ofwaveguide 150 that reflects light signal 104 out of waveguide 150 andtoward substrate 184 (as illustrated by the dotted lines). The sectionof waveguide 150 through which light signal 104 exits the waveguide maybe referred to herein as an “output section” of waveguide 150.

As shown, an angle between side 150 c and the tilted edge of side 150 bis an acute angle. In one embodiment, the acute tilting angle of tiltededge 150 b is 45 degrees. However, other tilting angles are possible aswell.

As illustrated by the dotted lines in FIG. 1B, waveguide 151 receiveslight signal 104 at an “input section” of waveguide 151 aligned with theoutput section of waveguide 150. In the example shown, the input sectionof waveguide 151 may correspond to a section of waveguide 151 thatoverlaps the output section (from which light signal 104 exits waveguide150). In alternate examples however, the input section of waveguide 151does not necessarily overlap waveguide 150. For instance, waveguide 150may be configured to transmit light signal 104 in a different directionthan the z-direction illustrated in FIG. 1B. In this instance, the inputsection of waveguide 151 may be aligned to intercept light signal 104from waveguide 150 at a different location (e.g., depending on thelocation of the output section and the direction at which light signal104 exits waveguide 150).

In the example shown, waveguide 151 is disposed on substrate 184 andshaped to define a second optical path (in the x-direction) on substrate184. Further, as shown, waveguide 151 includes a tilted edge 151 a (onwhich mirror 161 is disposed) at or near the input section of waveguide151. Thus, mirror 161 may be configured as an input mirror of waveguide151, which reflects light signal 104 (or portions thereof) incident onmirror 161 back into waveguide 151 and toward an output section ofwaveguide 151 (e.g., side 151 b). In the example shown, the secondoptical path defined by waveguide 151 extends in the x-direction towardan output section of waveguide 151 (e.g., side 151 b).

As shown, waveguide 152 is disposed in a same layer of system 100 aswaveguide 150 (i.e., on side 186 a of substrate 186). Waveguide 152 mayextend through the page (i.e., in the y-direction) to define a thirdoptical path inside waveguide 152. For example, waveguide 152 may beconfigured to guide a second light signal different than light signal104 along the third optical path. In this example, waveguide 152 extendsin a direction (e.g., y-direction) that is non-parallel to the guidingdirection (e.g., x-direction) of waveguide 150, 151). Further, as shown,a first section of waveguide 152 overlaps a second section of waveguide151. For example, the first section may be less than a thresholddistance to the second section.

Thus, in this example arrangement, the multi-layer optical system 100defines a combined optical path for light signal 104 extending in thex-direction from emitter 140 to side 151 b of waveguide 151. A firstpart of this combined optical path is in a first layer of multi-layersystem 100 (i.e., on substrate 186); and a second part of the combinedoptical path is in a second layer (i.e., on substrate 184).Additionally, system 100 defines a separate non-parallel optical pathwithin waveguide 152, which does not intersect the combined optical pathof light signal 104 (e.g., the two paths cross below or above oneanother in different layers of system 100).

FIG. 1C illustrates another cross-section view of system 100. Forpurposes of illustration, FIG. 1C shows x-y-z axes, where the z-axisextends through the page. For example, in the cross-section view ofsystem 100 of FIG. 1C, side 186 a of substrate 186 may be parallel tothe surface of the page, and light signal 104 (shown as the shadedregion on waveguide 150) propagates out of the page toward substrate 184(not shown in FIG. 1C). It is noted that one or more components ofsystem 100 are omitted from one or more of the illustrations in FIGS.1A-1C for convenience in description. Additionally, it is noted that thesizes, shapes, and positions of the various components of system 100illustrated in FIGS. 1A-1C are not necessary to scale but areillustrated as shown for convenience in description.

As shown, system 100 includes one or more additional components disposedon side 186 a of substrate 186. In particular, as shown, system 100 alsoincludes an optical element 132, a light emitter 142, a waveguide 154,and a mirror 164. Light emitter 142 may include any light sourcesimilarly to light emitter 140, and may be configured to emit a secondlight signal 106. Mirror 164 may be formed similarly to any of mirrors160, 161. In alternative examples, as noted above in the description ofmirrors 160, 161, system 100 can be implemented without mirror 164(e.g., edge 154 c may be configured as a TIR mirror that internallyreflects light 106 a incident thereon without the presence of mirror164, etc.).

Optical element 132 may be interposed between light emitter 142 andwaveguides 152, 154, and may be configured to redirect, focus,collimate, and/or otherwise adjust optical characteristics of emittedlight 106. To that end, optical element 132 may comprise any combinationof optical elements, such as lenses, mirrors, cylindrical lenses, lightfilters, etc.

In one example, optical element 132 may comprise a cylindrical lens,and/or other optical element configured to (at least partially)collimate and/or direct light beams in light signal 106 (e.g., emittedby emitter 142) as light portions 106 a and 106 b toward waveguides 154and 152, respectively. For instance, optical element 132 may transmit arelatively larger amount of energy from emitted light portion 106 b intowaveguide 152 by collimating the light beams. Alternatively oradditionally, for instance, optical element 132 may direct emitted lightportion 106 b into waveguide 152 at a particular angle of entry (e.g.,less than the critical angle of waveguide 460, etc.) that is suitablefor light beam(s) 106 b to be guided inside waveguide 152 (e.g., viatotal internal reflection, etc.).

By way of example, in the embodiment shown, optical element 132 isarranged substantially parallel to input side 152 a of waveguide 152(e.g., parallel to the y-axis). In alternative embodiments, opticalelement 132 could instead be tilted at an offset from the y-axis toadjust an angle-of-entry of light beam 106 b at input end 152 a ofwaveguide 152. In one particular embodiment, the angle-of-entry of lightportion 106 b is between 0 degrees and 6 degrees (e.g., 4 degrees,etc.). Other angles-of-entry of light portion 106 b are possible.

As shown, optical element 132 can be implemented as a single opticalelement interposed between emitter 142 and waveguides 152, 154. Forexample, optical element 132 can be implemented as an optical fiberarranged as a cylindrical lens configured to at least partiallycollimate light portions 106 a, 106 b. In other embodiments, opticalelement 132 can be alternatively implemented as multiple physicallyseparate optical elements (e.g., multiple cylindrical lenses and/orother types of optical elements).

In the example shown, waveguide 152 extends lengthwise to guide lightportion 106 b from input end 152 a to output end 152 b and extendswidthwise between a first wall (which includes edge 152 c) and a secondwall opposite the first wall. Thus, in this example, waveguide 152 maybe configured to receive light 106 b at input end 152 a and transmitlight 106 b out of waveguide 152 at output end 152 b. In alternativeexamples, light portion 106 b can be received at an input of waveguide152 that corresponds to any portion of the waveguide (e.g., surface,edge, location, section, etc.) at which light portion 106 b is incidenton the waveguide. Similarly, in alternative examples, an output ofwaveguide 152 may instead correspond to any location, surface, edge, orsection of waveguide 152 at which light portion 106 b exits thewaveguide.

In the example shown, a first section 152P of waveguide 152 extendslengthwise in a first direction (e.g., the section parallel to thex-axis between edge 152 a and edge 152 c), a second section 152Q ofwaveguide 152 extends lengthwise in a second direction different thanthe first direction (e.g., the middle section parallel to the y-axis),and a third section 152R of waveguide 152 extends lengthwise in a thirddirection different than the second direction (e.g., the sectionparallel to the x-axis between the second section and edge 152 b). Thus,in this example, waveguide 152 may be configured to guide light 106 binside the first section 152P toward the second section 152Q, inside thesecond section 152Q toward the third section 152R, and inside the thirdsection 152R away from the second section 152Q. In alternative examples,waveguide 152 may instead include fewer or more sections, and/or one ormore sections of the waveguide may extend in different directions thanthose described above. Thus, in some examples, various configurationsand/or shapes of waveguide 152 can be employed to accommodate differentarrangements, locations, and/or combinations of components mounted onsubstrate 186.

In the example shown, the third direction of the third section 152R ofwaveguide 152 is substantially parallel to the first direction of thefirst section 152P (e.g., both sections are shown to extend parallel tothe x-axis). In alternative examples, as noted above, the firstdirection and the third direction are not necessarily parallel to oneanother.

Edge 152 c may be tilted at a first angle 170 to the first section 152Pof waveguide 152 at the first wall different than a second angle 172between the first section 152P and the second section 152Q at the secondwall. For example, as shown, angle 170 may be greater than angle 172.With this arrangement for instance, light signal 106 b guided inside thefirst section 152P may be incident on edge 152 c from one or moreangles-of-incidence suitable for internal reflection (e.g., TIR) oflight 106 b toward the second section 152Q of waveguide 152, as opposedto propagating out of the waveguide at edge 152 c if the angles-ofincidence were instead greater than the critical angle.

To that end, in some examples, the angle 170 at which edge 152 c istilted may vary according to one or more optical characteristics ofoptical system 100. In a first example, tilting angle 170 may be basedon one or more wavelengths of light 106 b, a refractive index of theoptical material of waveguide 152, a refractive index of an opticalmedium (e.g., air, optical adhesive, etc.) adjacent to edge 152 c,and/or any other optical property of system 100 that affects thecritical angle at which total internal reflection of light 106 b at edge152 c may occur. In a second example, tilting angle 170 may be selectedbased on an angle-of-entry of light beam 106 b at input end 152 a (whichmay affect the angles-of-incidence of light 106 b upon arrival at edge152 c). For instance, as noted above, optical element 132 can be tiltedto an offset the angle-of-entry of light beam 106 b relative to anoptical axis of the first section 152P (e.g., relative to the firstdirection). In a third example, tilting angle 170 can be based at leastin part on the second direction of the second section 152Q of waveguide152 (e.g., the middle section parallel to the y-axis). In oneembodiment, angle 170 may be approximately 45 degrees and angle 172 maybe approximately 90 degrees. However, other values of angles 170, 172are possible as well.

In the example shown, edge 152 c is a flat edge. In alternativeexamples, edge 152 c may have a different shape than the flat shapeshown in FIG. 1C (e.g., curved edge, etc.).

Although not shown, in some examples, system 100 may also include amirror disposed on edge 152 c. In these examples, the mirror may beconfigured to reflect at least a portion of light signal 106 b exitingwaveguide 152 at edge 152 c back into waveguide 152 and into the secondsection 152Q of the waveguide (e.g., in the second direction of thesecond section that is parallel to the y-axis, etc.). To that end, forexample, the mirror may be similar to any of mirrors 160, 161 disposed,respectively, on the tilted edges of waveguides 150, 151 (as best shownin FIG. 1B).

As shown in FIG. 1C, waveguide 152 also includes a tilted edge 152 d (onthe second wall) between the second section 152Q and the third section152R of the waveguide. In line with the discussion above for edge 152 c,edge 152 d may be tilted at a suitable angle from the second section152Q (e.g., greater than the angle between the second section and thethird section at the first wall, etc.) to facilitate redirecting lightsignal 106 b from the second section 152Q into the third section 152R(e.g., via TIR of light signal 106 b at edge 152 d, etc.).

As shown in FIG. 1C, in some examples, the third section 152R ofwaveguide 152 may be tapered such that a cross-sectional size of thethird section 152R at output end 152 b is less than the cross-sectionalsize of the third section 152R at a given distance to output end 152 b.With this arrangement for instance, the taper configuration of the thirdsection 152R may facilitate reducing a beam width of light beam 106 btransmitted out of the waveguide at output end 152 b. In alternativeexamples, the third section 152R of waveguide 152 may be untapered ormay have a different taper configuration.

Although not shown, in some examples, one or more other sections ofwaveguide 152 may be tapered. In one example, the first section 152P ofwaveguide 152 (e.g., between input end 152 a and edge 152 c) may betapered such that a cross-sectional size of the first section 152P atthe input end 152 a is less than the cross-sectional size of the firstsection 152P at a given distance from the input end 152 a. With suchtaper configuration for instance, the width of the first section 152Pmay increase in the lengthwise guiding direction (i.e., first direction)of the first section 152P to reduce and/or mitigate signal leakageassociated with divergence of the guided light portion 106 b inside thefirst section 152P. Alternatively, in other examples, the first section152P may have a different taper configuration, or may have an untaperedconfiguration (such as the configuration shown in FIG. 1C).

In some examples, one or more walls (or edges) of any of waveguides 150,151, 152, and/or 154 may include a grating.

In one example, edge 152 c may include a diffraction grating. Forinstance, edge 152 c may be shaped according to a grating pattern thatcauses incident light thereon to be reflected and/or diffracted in aparticular manner (e.g., in a non-normal direction, etc.). In thisexample, the grating pattern on edge 152 c may thus facilitate selectinga different angle 172 than the angle shown and/or otherwise redirectinglight incident on the edge into section 152Q.

In another example, edge 152 c may be alternatively shaped to have agrating pattern that selectively transmits a first portion of the guidedlight out of waveguide 152 at edge 152 c based on the first portionhaving a particular wavelength (or being within a wavelength range)associated with the grating pattern. Thus, in this example, waveguide152 may be configured to direct the first portion out of the waveguideat edge 152 c, and to direct a second portion of the guided light intosection 152Q based on the second portion having different wavelength(s)than the wavelength(s) of the first portion.

In other examples, waveguides 150, 151, 152, and/or 154 may similarlyinclude one or more diffraction gratings at one or more walls and/oredges of the waveguides. For example, edge 154 c may alternativelyinclude a diffraction grating configured to reflect guided light 106 aincident thereon toward edge 154 d without the presence of mirror 164.Other examples are possible.

As noted above, in some implementations, the waveguides 150, 151, 152,154, etc. may be formed by selectively etching photoresist materialdisposed on the substrates.

In one implementation, a grating pattern can be included in a particularsidewall (or edge) of a waveguide based on features of a mask thatfilters exposure light applied to cure the portion of the photoresistmaterial that corresponds to the waveguide.

In another implementation, a surface relief grating (SRG) can be appliedon a particular region of substrates 184, 186, etc. prior to depositingthe photoresist material on the substrate (and prior to exposing/curingthe portions of the photoresist material corresponding to thewaveguides). When photoresist material is then disposed on the substratefor instance, the SRG could define the grating pattern of a wall of thewaveguide corresponding to a portion of the photoresist materialdisposed on the SRG.

With this arrangement, referring back to FIG. 1B for example, edge 150 bof waveguide 150 may alternatively be implemented without mirror 160 andwithout being tilted edge 150 c. For instance, a region of substrate 186at the output end of waveguide 150 can be etched according to aparticular grating pattern as the SRG. In this example, guided light canbe transmitted out of waveguide 150 by diffracting at the grated portionof the waveguide where the SRG is located (e.g., instead of beingreflected by mirror 160).

In an alternate example, instead of etching the substrate to form theSRG, the SRG can be implemented as a solid structure (e.g., plastic orother optical structure having a different index of refraction than thephotoresist material) that is disposed on the substrate prior todepositing the photoresist material.

Waveguide 154 may be formed similarly to any of waveguides 150, 151, and152, and may define another optical path for another portion 106 a oflight 106.

In the example shown, waveguide 154 extends lengthwise from input end154 a to output end 154 b; and extends widthwise between a first wall(which includes flat edge 154 c) and a second wall (which includescurved edge 154 d) opposite the first wall. Thus, in this example,waveguide 154 may be configured to receive light 106 a at input end 154a and transmit light 106 a out of waveguide 154 at output end 154 b. Inalternative examples, light portion 106 a can be received at an input ofwaveguide 154 that corresponds to any portion of the waveguide (e.g.,surface, edge, location, section, etc.) at which light portion 106 a isincident on the waveguide. Similarly, in alternative examples, an outputof waveguide 154 may instead correspond to any location, surface, edge,or section of waveguide 154 at which light portion 106 a exits thewaveguide.

In the example shown, input side 154 a includes a curved surface (e.g.,curved away from waveguide 154). With this configuration for instance,input end 154 a may focus and/or redirect light 106 a incident thereoninto the waveguide according to the curved shape of input surface 154 a.Thus, in some embodiments, a curvature configuration of input side 151 acan be selected to facilitate controlling the divergence and/ordirection of light beam 106 a entering the waveguide.

In alternative examples, input end 154 a may instead include a flat edgesimilarly to input end 152 a of waveguide 152. Further, in someexamples, input end 152 a of waveguide 152 may similarly have a curvedsurface instead of the flat surface shown in FIG. 1C.

In the example shown, a first section 154P of waveguide 154 extendslengthwise in a first direction (e.g., the section parallel to thex-axis between edge 154 a and edge 154 c); a second section 154Q ofwaveguide 154 extends lengthwise in a second direction different thanthe first direction (e.g., the middle section); and a third section 154Rof waveguide 154 extends lengthwise in a third direction different thanthe second direction (e.g., the section parallel to the x-axis betweenthe second section and edge 154 b). Thus, in this example, waveguide 154may be configured to guide light 106 a inside the first section 154Ptoward the second section 154Q, inside the second section 154Q towardthe third section 154R, and inside the third section 154R away from thesecond section 154Q. In alternative examples, waveguide 154 may insteadinclude fewer or more sections, and/or one or more sections of thewaveguide may extend in different directions than shown in FIG. 1C.Thus, in some examples, various configurations and/or shapes ofwaveguide 154 can be employed to accommodate different arrangements,locations, and/or combinations of components mounted on substrate 186.

In the example shown, the second section 154Q of waveguide 154 has aflat edge 154 c (in the first wall) that is tilted at a third angle 174relative to the first section 154P of waveguide 154, and a curved edge154 d (in the second wall) opposite the flat edge 154 c. As shown, thethird angle 174 may be different than a fourth angle 176 between thefirst section 154P of waveguide 154 and the second section 154Q ofwaveguide 154 (at the second wall).

As shown, mirror 164 may be disposed on flat edge 154 c. For example,mirror 164 may be configured to receive at least a portion light signal106 a incident on flat edge 154 c from the first section 154P ofwaveguide 154 and transmitted out from the waveguide at the flat edge.Mirror 164 may then reflect the received light 106 a incident thereonback into the waveguide and toward the curved edge 154 d. In thisexample, curved edge 154 d may then reflect (e.g., via TIR) the light106 a incident thereon toward the third section 154R of waveguide 154.For example, curved edge 154 d may be curved away from waveguide 154 todefine a concave-shaped surface inside the waveguide that reflects(and/or focuses) incident portions of light 106 a into the third section154R of waveguide 154. In this way, for instance, the curved edge 154 dmay facilitate controlling/reducing a beam width of light beam 106 aexiting the waveguide at output end 154 b by “funneling” the lightsignal 106 a into the third section 154R. Thus, in the example shown, across-sectional size of the third section 154R of waveguide 154 (e.g.,at output end 154 b, etc.) may be less than a cross-sectional size ofthe first section 154P of waveguide 154 (e.g., at input end 154 a,etc.).

In alternative examples, system 100 may be implemented without mirror164. For instance, tilting angle 174 can be selected such that light 106a is incident on edge 154 c from one or more angles-of-incidencesuitable for internally reflecting light 106 a (e.g., via TIR) at edge154 c toward edge 154 d (e.g., instead of being reflected from mirror164).

In some examples, edge 154 c of the second section 154Q mayalternatively be configured as a curved edge (e.g., similarly to edge154 d) instead of having a flat edge configuration as shown in theexample of FIG. 1C).

In a first example, edge 154 c may be curved away from waveguide 154 todefine a concave surface (inside the waveguide) that redirects (and/orfocuses) light 106 a incident thereon (e.g., via TIR) toward curved edge154 d. With this configuration for instance, the curved edge 154 c mayfurther facilitate “funneling” light 106 a, in line with the discussionabove in the description of curved edge 154 d. Further, in the firstexample, system 100 could thus be implemented without a mirror 164(e.g., edge 154 c may correspond to a TIR mirror, etc.).

Alternatively, in a second example, edge 154 c may have the curvedconfiguration of the first example and system 100 may also includemirror 164. For instance, in the second example, mirror 164 may bealternatively configured as a curved mirror (e.g., concave mirror)disposed on curved edge 154 c (instead of having the flat mirrorconfiguration shown).

In a third example, edge 154 c can be alternatively curved inwards(i.e., toward the waveguide) to define a convex surface 154 c inside thewaveguide. Other examples and/or shapes of edge 154 c are possible aswell.

As noted above, an optical system such as system 100 can be employed forrouting optical signals for a wide variety of devices in varioustechnology fields, such as light detection and ranging (LIDAR) devices,medical imaging devices, data communication systems, among otherexamples.

FIG. 2A is a simplified block diagram of a LIDAR device 200, accordingto example embodiments. In some examples, LIDAR device 200 can bemounted to a vehicle and employed to map a surrounding environment(e.g., a scene including object 298, etc.) of the vehicle. As shown,LIDAR 200 includes a laser emitter 240 that may be similar to emitter140, an optical system 290, a controller 292, a rotating platform 294,and one or more actuators 296.

System 290 includes one or more light detectors 210, an opaque material220, and a lens 230. It is noted that LIDAR device 200 may alternativelyinclude more or fewer components than those shown, such as any of thecomponents described for system 100 (e.g., waveguides, etc.).

Detector(s) 210 may include one or more light detectors. In oneembodiment, detector(s) 210 include an array of light detectors thatdefine a detection region for detecting the light 202 focused by lens230. Additionally, light detector(s) 210 may include various types oflight detectors, such as photodiodes, single photon avalanche diodes(SPADs), other types of avalanche photodiodes (APDs), siliconphotomultipliers (SiPMs), multi-pixel photon counters (MPPCs),photoresistors, charge-coupled devices (CCDs), photovoltaic cells,and/or any other type of light detector.

Opaque material 220 (e.g., mask, aperture stop, etc.) may block aportion of light 202 returning from the scene (e.g., background light)and focused by the lens 230 from being transmitted to detector(s) 210.For example, opaque material 220 may be configured to block certainbackground light that could adversely affect the accuracy of ameasurement performed by detector(s) 210. Alternatively or additionally,opaque material 220 may block light in the wavelength range detectableby detector(s) 210, etc. In one example, opaque material 220 may blocktransmission by absorbing a portion of incident light. In anotherexample, opaque material 220 may block transmission by reflecting aportion of incident light. A non-exhaustive list of exampleimplementations of opaque material 220 includes an etched metal, apolymer substrate, a biaxially-oriented polyethylene terephthalate(BoPET) sheet, or a glass overlaid with an opaque mask, among otherpossibilities. In some examples, opaque material 220 may include one ormore apertures through which focused light 202 (or a portion thereof)may be transmitted through opaque material 220.

Lens 230 may focus light 202 returning from the scene toward theaperture of opaque material 220. With this arrangement, the lightintensity collected from the scene, at lens 230, may be focused to havea reduced cross-sectional area over which light 202 is projected (i.e.,increased spatial power density of light 202). To that end, lens 230 mayinclude a converging lens, a biconvex lens, and/or a spherical lens,among other examples. Alternatively, lens 230 can be implemented as aconsecutive set of lenses positioned one after another (e.g., a biconvexlens that focuses light in a first direction and an additional biconvexlens that focuses light in a second direction). Other types of lensesand/or lens arrangements are also possible. In addition, system 290 mayinclude other optical elements (e.g., mirrors, etc.) positioned nearlens 230 to aid in focusing light 202 incident on lens 230 onto opaquematerial 220.

Device 200 may operate emitter 240 to emit light 202 toward a scene thatincludes object 298. To that end, in some implementations, emitter 240(and/or one or more other components of device 200) can be configured asa LIDAR transmitter of LIDAR device 200. Device 200 may then detectreflections of light 202 returning from the scene to determineinformation about object 298. To that end, in some implementations,detector(s) 210 (and/or one or more other components of system 290) canbe configured as a LIDAR receiver of LIDAR device 200.

Controller 292 may be configured to control one or more components ofLIDAR device 200 and to analyze signals received from the one or morecomponents. To that end, controller 292 may include one or moreprocessors (e.g., a microprocessor, etc.) that execute instructionsstored in a memory (not shown) of device 200 to operate device 200.Additionally or alternatively, controller 292 may include digital oranalog circuitry wired to perform one or more of the various functionsdescribed herein.

Rotating platform 294 may be configured to rotate about an axis toadjust a pointing direction of LIDAR 200 (e.g., direction of emittedlight 202 relative to the environment, etc.). To that end, rotatingplatform 294 can be formed from any solid material suitable forsupporting one or more components of LIDAR 200. For example, system 290(and/or emitter 240) may be supported (directly or indirectly) byrotating platform 294 such that each of these components moves relativeto the environment while remaining in a particular relative arrangementin response to rotation of rotating platform 294. In particular, themounted components could be rotated (simultaneously) about an axis sothat LIDAR 200 may adjust its pointing direction while scanning thesurrounding environment. In this manner, a pointing direction of LIDAR200 can be adjusted horizontally by actuating rotating platform 294 todifferent directions about the axis of rotation. In one example, LIDAR200 can be mounted on a vehicle, and rotating platform 294 can berotated to scan regions of the surrounding environment at variousdirections from the vehicle.

In order to rotate platform 294 in this manner, one or more actuators296 may actuate rotating platform 294. To that end, actuators 296 mayinclude motors, pneumatic actuators, hydraulic pistons, and/orpiezoelectric actuators, among other possibilities.

With this arrangement, controller 292 could operate actuator(s) 296 torotate rotating platform 294 in various ways so as to obtain informationabout the environment. In one example, rotating platform 294 could berotated in either direction about an axis. In another example, rotatingplatform 294 may carry out complete revolutions about the axis such thatLIDAR 200 scans a 360° field-of-view (FOV) of the environment. In yetanother example, rotating platform 294 can be rotated within aparticular range (e.g., by repeatedly rotating from a first angularposition about the axis to a second angular position and back to thefirst angular position, etc.) to scan a narrower FOV of the environment.Other examples are possible.

Moreover, rotating platform 294 could be rotated at various frequenciesso as to cause LIDAR 200 to scan the environment at various refreshrates. In one embodiment, LIDAR 200 may be configured to have a refreshrate between 3 Hz and 30 Hz. For example, where LIDAR 200 is configuredto scan a 360° FOV at a refresh rate of 10 Hz, actuator(s) 296 mayrotate platform 294 for ten complete rotations per second. Other refreshrates are possible.

FIG. 2B illustrates a perspective view of LIDAR device 200. In someembodiments, device 200 may be configured to include a single sharedlens 230 for both directing emitted light from emitter 240 toward theenvironment and focusing incident light 202 into system 290. In otherembodiments, device 200 may include a separate transmitter lens (notshown) for directing the emitted light 240 different than the lens 230.

As shown in FIG. 2B, LIDAR 200 may be configured to rotate about an axisof rotation 201. In this way, LIDAR 200 can scan different regions ofthe surrounding environment according to different rotational positionsof LIDAR 200 about axis 201. For instance, device 200 (and/or anothercomputing system) can determine a three-dimensional map of a 360° (orless) view of the environment of device 200 by processing dataassociated with different pointing directions of LIDAR 200 as the LIDARrotates about axis 201.

In some examples, axis 201 may be substantially vertical. In theseexamples, the pointing direction of device 200 can be adjustedhorizontally by rotating system 290 (and emitter 240) about axis 201.

In some examples, system 290 (and emitter 240) can be tilted (relativeto axis 201) to adjust the vertical extents of the FOV of LIDAR 200. Byway of example, LIDAR device 200 can be mounted on top of a vehicle. Inthis example, system 290 (and emitter 240) can be tilted (e.g., towardthe vehicle) to collect more data points from regions of the environmentthat are closer to a driving surface on which the vehicle is locatedthan data points from regions of the environment that are above thevehicle. Other mounting positions, tilting configurations, and/orapplications of LIDAR device 200 are possible as well (e.g., on adifferent side of the vehicle, on a robotic device, or on any othermounting surface).

Returning now to FIG. 2A, in some implementations, controller 292 mayuse timing information associated with a signal measured by array 210 todetermine a location (e.g., distance from LIDAR device 200) of object298. For example, in embodiments where emitter 240 is a pulsed laser,controller 292 can monitor timings of output light pulses and comparethose timings with timings of signal pulses measured by array 210. Forinstance, controller 292 can estimate a distance between device 200 andobject 298 based on the speed of light and the time of travel of thelight pulse (which can be calculated by comparing the timings). In oneimplementation, during the rotation of platform 294, emitter 240 mayemit light pulses (e.g., light 202), and system 290 may detectreflections of the emitted light pulses. Device 200 (or another computersystem that processes data from device 200) can then generate athree-dimensional (3D) representation of the scanned environment basedon a comparison of one or more characteristics (e.g., timing, pulselength, light intensity, etc.) of the emitted light pulses and thedetected reflections thereof.

It is noted that the various functional blocks shown for the componentsof device 200 can be redistributed, rearranged, combined, and/orseparated in various ways different than the arrangement shown.

FIG. 3A is an illustration of a system 300 that includes a waveguide350, according to example embodiments. FIG. 3B illustrates across-section view of the system 300. In some implementations, system300 can be included in device 200 instead of or in addition totransmitter 240 and system 290. As shown, system 300 may measure light302 reflected by an object 398 within a scene similarly to,respectively, device 200, light 202, and object 298. Further, as shown,system 300 includes a light detector array of light detectors 310, anopaque material 320, a lens 330, and a light source 340, which may besimilar, respectively, to detector(s) 210, material 220, lens 230, andemitter 240.

As shown, system 100 also includes an aperture 320 a defined withinopaque material 320. For the sake of example, aperture 320 a is shown tohave an elliptical shape. However, other aperture shapes are possible(e.g., circular, rectangular, or any other shape). Aperture 320 aprovides a port within opaque material 320 through which light may betransmitted. Aperture 320 a may be defined within opaque material 320 ina variety of ways. In one example, opaque material 320 (e.g., metal,etc.) may be etched to define aperture 320 a. In another example, opaquematerial 320 may be configured as a glass substrate overlaid with amask, and the mask may include a gap that defines aperture 320 a (e.g.,via photolithography, etc.). In various embodiments, aperture 320 a maybe partially or wholly transparent, at least to wavelengths of lightthat are detectable by light detector array 310. For example, whereopaque material 320 is a glass substrate overlaid with a mask, aperture320 a may be defined as a portion of the glass substrate not covered bythe mask, such that aperture 320 a is not completely hollow but rathermade of glass. Thus, in some instances, aperture 320 a may be partially,but not entirely, transparent to one or more wavelengths of light 302.Alternatively, in some instances, aperture 320 a may be formed as ahollow region of opaque material 320. Other aperture implementations arepossible.

As shown, system 300 also includes waveguide 350 (e.g., opticalwaveguide, etc.), which may be similar to any of waveguides 150, 151,and/or 152. As shown, system 300 also includes an input mirror 360 andan output mirror 370, which may be similar to any of mirrors 160 and/or161.

In the example shown, waveguide 350 is positioned between opaquematerial 320 and array 310. However, in other examples, opaque material320 can be instead positioned between waveguide 350 and array 310. Asshown, waveguide 350 may be arranged such that a portion of waveguide350 extends into a propagation path of focused light 302, and anotherportion of waveguide 350 extends outside the propagation path of focusedlight 302. As a result, a first portion of focused light 302 transmittedthrough aperture 320 a may be projected onto waveguide 350 (asillustrated by the shaded region on the surface of waveguide 350).

As best shown in FIG. 3B, a second portion of focused light 302 maypropagate from lens 330 to array 310 without propagating throughwaveguide 350.

In some instances, at least part of the first portion of focused light302 (projected onto waveguide 350) may propagate through transparentregions of waveguide 350 (e.g., from side 350 c to side 350 d and thenout of waveguide 350 toward array 310, without being intercepted bymirror 370. However, in some instances, the first portion of focusedlight 302 may be at least partially intercepted by mirror 370 and thenreflected away from array 310 (e.g., guided inside waveguide 350, etc.).

To mitigate this, in some examples, mirror 370 can be configured to havea small size relative to aperture 320 a and/or relative to a projectionarea of focused light 302 at the location of mirror 370. In theseexamples, a larger portion of focused light 302 may propagate adjacentto mirror 370 (and/or waveguide 350) to continue propagating towardarray 310. Alternatively or additionally, in some examples, mirror 370can be formed from a partially or selectively reflective material (e.g.,half mirror, dichroic mirror, polarizing beam splitter, etc.) thattransmits at least a portion of focused light 302 incident thereonthrough mirror 370 for propagation toward array 310. Thus, in theseexamples as well, a larger amount of focused light 302 may eventuallyreach array 310.

In some examples, input mirror 360 may be configured to direct emittedlight 304 (intercepted by mirror 360 from emitter 340) into waveguide350. Waveguide 350 then guides light 304 inside waveguide 350 towardoutput mirror 370. Output mirror 370 may then reflect guided light 304out of waveguide 350 and toward aperture 320 a.

As best shown in FIG. 3B for example, input mirror 360 may be tilted atan offset angle 359 toward side 350 c of waveguide 350. For example, anangle between mirror 360 and side 350 c may be less than an anglebetween mirror 360 and side 360 d. In one implementation, offset ortilting angle 359 of mirror 360 is 45°. However, other angles arepossible. In the embodiment shown, input mirror 360 is disposed on side350 a of waveguide 350. Thus, in this embodiment, emitted light 304 maypropagate into waveguide 350 through side 350 c and then out of side 350a toward mirror 360. Mirror 360 may then reflect light 304 back intowaveguide 350 through side 350 a at a suitable angle of entry so thatwaveguide 350 can then guide light 304 toward side 350 b. For example,waveguide 350 can be formed such that angle 359 between sides 350 a and350 c is less than the angle between side 350 a and side 350 d (i.e.,side 350 a tilted toward side 350 c). Input mirror 360 can then bedeposited onto side 350 a (e.g., via chemical vapor deposition,sputtering, mechanical coupling, or another process). However, in otherembodiments, mirror 360 can be alternatively disposed inside waveguide350 (e.g., between sides 350 a and 350 b), or may be physicallyseparated from waveguide 350.

As best shown in FIG. 3B, output mirror 370 may also be tilted towardside 350 c of waveguide 350. For example, an angle 371 between mirror370 and side 350 c may be less than an angle between mirror 370 and side360 d. In one implementation, offset or tilting angle 371 of mirror 370is 45°. However, other angles are possible. Thus, in some examples,input mirror 360 may be tilted in a first direction (e.g., clockwise inthe view of FIG. 3B) toward side 350 c, and output mirror 370 may betilted in a second direction (e.g., opposite to the first direction)toward side 350 c. Output mirror 370 can be physically implemented invarious ways similarly to mirror 360 (e.g., disposed on tilted side 350b of waveguide 350, etc.).

In some examples, waveguide 350 may be formed from a material that has adifferent index of refraction than that of materials surroundingwaveguide 350. Thus, waveguide 350 may guide at least a portion of lightpropagating inside the waveguide via internal reflection (e.g., totalinternal reflection, frustrated total internal reflection, etc.) at oneor more edges, sides, walls, etc., of waveguide 350. For instance, asshown in FIG. 3B, waveguide 350 may guide emitted light 304 (receivedfrom emitter 340) toward side 350 b via internal reflection at sides 350c, 350 d, and/or other sides of waveguide 350.

As shown in FIG. 3B, aperture 320 a could be located adjacent to anoutput section of waveguide 350 to transmit light 304 toward lens 330.Lens 330 may then direct light 304 toward a scene. Emitted light 304 maythen reflect off one or more objects (e.g., object 398) in the scene,and return to lens 330 (e.g., as part of light 302 from the scene). Lens330 may then focus light 302 (which includes reflections of the emittedlight 304) through aperture 320 a and toward array 310.

With this arrangement, system 300 may emit light 304 from asubstantially same physical location (e.g., aperture 320 a) from whichsystem 300 receives focused light 302 (e.g., aperture 320 a). Becausethe transmit path of emitted light 304 and the receive path of focusedlight 302 are co-aligned (e.g., both paths are from the point-of-view ofaperture 320 a), system 300 may be less susceptible to the effects ofparallax. For instance, data from a LIDAR device that includes system300 could be used to generate a representation of the scene (e.g., pointcloud) that is less susceptible to errors related to parallax.

It is noted that the sizes, positions, orientations, and shapes of thecomponents and features of system 300 shown are not necessarily toscale, but are illustrated as shown only for convenience in description.It is also noted that system 300 may include fewer or more componentsthan those shown, and one or more of the components shown could bearranged differently, physically combined, and/or physically dividedinto separate components.

In a first embodiment, waveguide 350 can alternatively have acylindrical shape or any other shape. Additionally, in some examples,waveguide 350 can be implemented as a rigid structure (e.g., slabwaveguide) or as a flexible structure (e.g., optical fiber). In a secondembodiment, waveguide 350 may have a curved shape or other type of shapeinstead of the vertical rectangular configuration shown in FIGS. 3A and3B. In a third embodiment, waveguide 350 can be alternativelyimplemented without a tilted edge 350 a. For example, side 350 a can beat a same (e.g., perpendicular, etc.) angle relative to sides 350 c and350 d. In a fourth embodiment, mirrors 360, 370 can be omitted fromsystem 300, and waveguide 350 can instead be configured to perform thefunctions described above for mirrors 360, 370. For example, sides 350 aand 350 b of waveguide 350 can be implemented as TIR mirrors thatreflect light 304 into or out of waveguide 350.

FIG. 4A illustrates a first cross-section view of a system 400 thatincludes multiple waveguides, according to example embodiments. Forpurposes of illustration, FIG. 4A shows x-y-z axes, where the z-axisextends through the page. System 400 may be similar to systems 100, 290,and/or 300, and can be used with LIDAR device 200 instead of or inaddition to system 290 and transmitter 240.

As shown, system 400 includes transmitters 440 and 442, each of whichmay be similar to emitter 140; a plurality of waveguides 450, 452, 454,456, each of which may be similar to waveguide 150; and a plurality ofoutput mirrors 460, 462, 464, 466, each of which may be similar tomirror 160. In some examples, the optical components of system 400 shownin FIG. 4A may correspond to a first layer of optical componentsdisposed on a first substrate (e.g., substrate 186) of a plurality ofoverlapping substrates. Referring back to FIG. 1B for example, the sideof waveguide 450 extending along the surface of the page may be similarto side 150 c of waveguide 150.

In the example shown, transmitter 440 emits a first light signal 404,and transmitter 442 emits a second light signal 406. Waveguide 450receives and guides a first light portion 404 a of light signal 404toward mirror 460, which then reflects light portion 404 a out ofwaveguide 450 at an output section of the waveguide (illustrated as ashaded region of the waveguide) in the z-direction (i.e., out of thepage). Similarly, waveguide 452 guides a second light portion 404 b ofthe first light signal 404 along a second optical path; waveguide 454guides a third light portion 406 a of the second light signal 406 alonga third optical path; and waveguide 456 guides a fourth light portion406 b along a fourth optical path.

FIG. 4B illustrates a second cross-section view of system 400, where thez-axis also extends through the page. As shown in FIG. 4B, system 400also includes waveguides 451, 453, 455, 457, each of which may besimilar to waveguide 151 of system 100; input mirrors 461, 463, 465,467, each of which may be similar to mirror 161 of system 100; andoutput mirrors 470, 472, 474, 476, each of which may be similar tomirror 370 of system 300.

The optical components of system 400 shown in FIG. 4B may correspond toa second layer of optical components that overlaps the first layer ofoptical components shown in FIG. 4A. By way of example, referring backto FIG. 1B, the optical components of system 400 shown in FIG. 4A couldbe disposed on surface 186 a of substrate 186; and the opticalcomponents of system 400 shown in FIG. 4B could be disposed on surface184 a of substrate 184. In this example, the side of waveguide 451 alongthe surface of the page in FIG. 4B may be similar to a side of waveguide151 that is disposed on substrate 184 in FIG. 1B.

For instance, similarly to mirror 161 of system 100, input mirror 461 ofsystem 400 may receive light portion 404 a (transmitted out of waveguide450 as shown in FIG. 4A). Mirror 461 may then reflect the light portion404 a incident thereon back into waveguide 451, and the waveguide maythen guide light portion 404 a toward mirror 470. Similarly to outputmirror 370 of waveguide 350, output mirror 470 may then reflect lightportion 404 a out of waveguide 451 at an output section (shaded region)of the waveguide in the z-direction (out of the page).

Similarly, as shown in FIG. 4B, input mirror 463, waveguide 453, andoutput mirror 472 define an optical path for light portion 406 a; inputmirror 465, waveguide 455, and output mirror 474 define an optical pathfor light portion 404 b; input mirror 467, waveguide 457, and outputmirror 476 define an optical path for light portion 406 b.

FIG. 4C illustrates a third cross-section view of system 400, accordingto example embodiments. As shown in FIG. 4C, system 400 also includes anopaque material 420, which may be similar to opaque material 320 ofsystem 300. As shown in FIG. 4C, opaque material 420 defines a pluralityof apertures, exemplified by apertures 420 a, 420 b, 420 c, and 420 d,each of which may be similar to aperture 320 a. For example, aperture420 a may be aligned with output mirror 470 similarly to, respectively,aperture 320 a and output mirror 370. For instance, aperture 420 a mayoverlap output mirror 470 in the direction of the z-axis to receivelight 404 a reflected by output mirror 470 out of waveguide 450.Similarly, aperture 420 b can be aligned with output mirror 472 toreceive light portion 406 a, aperture 420 c could be aligned with outputmirror 474 to receive light portion 404 b, and aperture 420 d could bealigned with output mirror 476 to receive light portion 404 b. Thus,each aperture may be associated with a position of a respective transmitchannel of system 400.

Additionally, in some examples, light from a scene (e.g., propagatinginto the page in FIG. 4B) could be focused onto opaque material 420,similarly to light 302 that is focused onto opaque material 320. Inthese examples, system 400 may thus provide multiple receive channelsassociated with respective portions of the focused light projected onopaque material 420 at the respective positions of apertures 420 a, 420b, 420 c, 420 d, etc. For example, a first portion of the focused lighttransmitted through aperture 420 a could be intercepted by a first lightdetector associated with a first receive channel, a second portion ofthe focused light transmitted through aperture 420 b could beintercepted by a second light detector associated with a second receivechannel, a third portion of the focused light transmitted throughaperture 420 c could be intercepted by a third light detector associatedwith a third receive channel, and a fourth portion of the focused lighttransmitted through aperture 420 d could be intercepted by a fourthlight detector associated with a fourth receive channel.

With this arrangement, each transmit channel may be associated with atransmit path that is spatially co-aligned (through a respectiveaperture) with a receive path associated with a corresponding receivechannel.

FIG. 4D illustrates a fourth cross section view of system 400, in whichthe z-axis is also pointing out of the page. As shown in FIG. 4D, system400 also includes a support structure 480 that mounts a plurality ofreceivers, exemplified by receivers 410, 412, 414, and 416, each ofwhich may be similar to any of light detectors 210 and/or 310. Further,as shown, system 400 also includes one or more light shields 482.

Each of receivers 410, 412, 414, 416, 418, etc., may include one or morelight detectors. Additionally, each receiver may be arranged tointercept focused light transmitted through a respective aperture ofopaque material 420 (shown in FIG. 4C). For example, receivers 410, 412,414, 416 may be arranged to intercept focused light that is transmitted,respectively, through apertures 420 a, 420 b, 420 c, 420 d (shown inFIG. 4C). In one embodiment, receivers 410, 412, 414, 416 may bepositioned to overlap (e.g., in the direction of the z-axis),respectively, output mirrors 470, 472, 474, 476.

Support Structure 480 may include a solid structure that has materialcharacteristics suitable for supporting receivers 410, 412, 414, 416,etc. In one example, support structure 480 may include a printed circuitboard (PCB) to which the light detectors of receivers 410, 412, 414,416, 418, etc., are mounted.

Light shield(s) 482 may comprise one or more light absorbing materials(e.g., black carbon, black chrome, black plastic, etc.) arranged aroundreceivers 410, 412, 414, 416, etc. In some examples, light shield(s) 482may prevent (or reduce) light from external sources (e.g., ambientlight, etc.) from reaching receivers 410, 412, 414, 416, etc.Alternatively or additionally, in some examples, light shield(s) 482 mayprevent or reduce cross-talk between receive channels associated withreceivers 410, 412, 414, 416, etc. Thus, light shield(s) 482 may also beconfigured to optically separate receivers 410, 412, 414, 416, etc.,from one another.

Returning now to FIG. 4C, as noted above, opaque material 420 defines agrid of apertures 410, 412, 414, 416, etc. Thus, in some examples wheresystem 400 is included in a LIDAR device, each aperture in opaquematerial 420 may transmit light toward a respective portion of afield-of-view (FOV) of the LIDAR and also receive reflected portions ofthe transmitted light returning from that same respective portion of theFOV. Thus, each aperture may be associated with a transmit/receivechannel of the LIDAR. In one embodiment, opaque material 420 maycomprise four rows of 64 apertures, where each row of horizontally(e.g., along y-axis) adjacent apertures is separated by a verticaloffset (e.g., along z-axis) from another row of apertures. In thisembodiment, system 400 could thus provide 4*64=256 co-alignedtransmit/receive channels. In other embodiments, system 400 may includea different number of transmit/receive channels (and thus a differentnumber of associated apertures).

Additionally, the LIDAR in this example may have a plurality of lightemitters, each of which is assigned to one or more transmit/receivechannels. Referring back to FIG. 4A for instance, light emitter 440transmits light portions 404 a and 404 b for scanning thetransmit/receive channels associated with apertures 420 a and 420 c(shown in FIG. 4C); and light emitter 442 transmits light portions 406 aand 406 b for scanning the channels associated with apertures 420 b and420 d.

In line with the discussion above, an example LIDAR device that employssystem 400 may be configured to transmit a plurality of light beams 404a, 406 a, 404 b, 406 b, etc., in a relative spatial arrangement toward ascene (e.g., the spatial arrangement of apertures 420 a, 420 b, 420 c,420 d, etc., shown in FIG. 4C). Each of the transmitted light beams maycorrespond to a portion of (or all) the light emitted by a particularlight emitter. For example, as best shown in FIG. 4A, a first portion404 a of light 404 (emitted from light emitter 404) can be directed in acombined optical path defined by waveguides 450 and 451 toward a firsttransmit location (shaded region 404 a shown in FIG. 4B) of a firstlight beam in the relative spatial arrangement, and a second portion 404b of light 404 can be directed toward a second transmit location (shadedregion 404 b shown in FIG. 4B) of a second light beam in the relativespatial arrangement. In this way, a single light emitter 440 can be usedto drive two separate channels (e.g., the channels scanned via apertures420 a and 420 c shown in FIG. 4C) of the LIDAR that are relatively moredistant from one another (e.g., as compared to the adjacent channelsassociated with apertures 420 a and 420 b). For instance, with thisarrangement, a multi-channel LIDAR device of system 400 can mitigatescanning errors (e.g., crosstalk errors between multiple channelsilluminated using a single emitter, retroreflector errors associatedwith returning reflections from retroreflectors in the scene, etc.) byspatially separating the channels illuminated using the single emitter.

As noted above, one example LIDAR device herein may use system 400 totransmit a plurality of light beams in a relative spatial arrangement.To that end, for example, the LIDAR device may include a first waveguide(e.g., 453) configured to receive a first portion (e.g., 406 a) of afirst light signal (e.g., 406) emitted by a first light emitter (e.g.,442) and transmit the first light portion out of the first waveguide ata first transmit location (e.g., output of waveguide 453) of a firstlight beam in the relative spatial arrangement of light beams; and asecond waveguide (e.g., 457) configured to receive a second portion(e.g., 406 b) of the same light signal (e.g., 406) and transmit thesecond light portion out of the second waveguide at a second transmitlocation (e.g., output of waveguide 457) as a second light beam in therelative spatial arrangement. The example LIDAR device may also includea third waveguide (e.g., 451) configured to receive a second lightsignal (e.g., 404 a) emitted from a second light emitter (e.g., 440) andtransmit the second light signal out of the third waveguide at a thirdtransmit location (e.g., output of waveguide 451) as a third light beamof the plurality of light beams in the relative spatial arrangement.

In this example, as best shown in FIG. 4B, the first transmit locationof light beam 406 a may be at a first distance to the second transmitlocation of light beam 406 b; and the third transmit location of lightbeam 404 a may be at a second distance to the first transmit locationdifferent than the first distance. For example, as best shown in FIG.4B, the first distance (between beams 406 a and 406 b) may be greaterthan the second distance (between beams 404 a and 406 a).

In some examples, the plurality of light beams (e.g., 404 a, 406 a, 404b, 406 b, etc.) may be diverging light beams that diverge away from theLIDAR device of system 400. In these examples, the diverging light beamscould thus intersect at a given distance from the LIDAR device. As bestshown in FIG. 4B for example, light beams 404 a and 406 a may initiallyexit the LIDAR of system 400 as separate light beams that diverge awayfrom the LIDAR and eventually intersect one another at the givendistance from the LIDAR.

In some examples, one or more of waveguides 450, 451, 452, 453, 454,455,456, and/or 457 (and/or portions thereof) can be alternativelyconfigured similarly to any of the waveguides described in systems 100and/or 300. In a first example, waveguide 463 (shown in FIG. 4B), or aportion thereof, can be alternatively shaped similarly to waveguide 152and/or 154 (as best shown in FIG. 1C) to route light signal 406 athrough any of apertures 420 a, 420 b, 420 c, 420 d, etc., in anefficient manner (e.g., efficient use of space on a substrate, and/orreduced signal leakage between adjacent sections of the waveguide thatextend lengthwise in different directions, etc.). In a second example,waveguide 452 (shown in FIG. 4A), or a portion thereof, could bealternatively shaped and/or configured similarly to waveguide 154 (shownin FIG. 1C), or a portion thereof. In the second example, system 400could also optionally include a mirror (e.g., similar to mirror 164)disposed on a middle section of waveguide 452 similarly to mirror 164.Other examples are possible.

Thus, in some examples, a multi-layer optical system arrangement such asthe arrangements described for systems 100 and 400 can be employed in aLIDAR device (or other device that operates based on optical signals) toroute light signals from multiple light emitter to multiple spatiallyseparate transmit/channels via non-parallel optical paths (e.g., theoptical paths of light portions 406 a and 404 b) and in aspace-efficient manner.

It is noted that the sizes, shapes, and positions shown in FIGS. 4A-4Dfor the various components of system 400 are not necessarily to scalebut are illustrated as shown only for convenience in description.

III. EXAMPLE METHODS

FIG. 5 is a flowchart of a method 500, according to example embodiments.Method 700 presents an embodiment of a method that could be used withsystems 100, 290, 300, 400, and/or device 200, for example. Method 500may include one or more operations, functions, or actions as illustratedby one or more of blocks 502-508. Although the blocks are illustrated ina sequential order, these blocks may in some instances be performed inparallel, and/or in a different order than those described herein. Also,the various blocks may be combined into fewer blocks, divided intoadditional blocks, and/or removed based upon the desired implementation.In addition, for method 500 and other processes and methods disclosedherein, the flowchart shows functionality and operation of one possibleimplementation of present embodiments. In this regard, each block mayrepresent a module, a segment, a portion of a manufacturing or operationprocess, or a portion of program code, which includes one or moreinstructions executable by a processor for implementing specific logicalfunctions or steps in the process. The program code may be stored on anytype of computer readable medium, for example, such as a storage deviceincluding a disk or hard drive. The computer readable medium may includea non-transitory computer readable medium, for example, such ascomputer-readable media that stores data for short periods of time likeregister memory, processor cache and Random Access Memory (RAM). Thecomputer readable medium may also include non-transitory media, such assecondary or persistent long term storage, like read only memory (ROM),optical or magnetic disks, compact-disc read only memory (CD-ROM), forexample. The computer readable media may also be any other volatile ornon-volatile storage systems. The computer readable medium may beconsidered a computer readable storage medium, for example, or atangible storage device. In addition, for method 500 and other processesand methods disclosed herein, each block in FIG. 5 may representcircuitry that is wired to perform the specific logical functions in theprocess.

At block 502, method 500 involves emitting, by a light emitter (e.g.,emitter 142), light (e.g., light 106 b) into a waveguide (e.g.,waveguide 152).

At block 504, method 500 involves guiding, inside a first section (e.g.,section 152P) of the waveguide, the light in a first direction (e.g.,parallel to x-axis in FIG. 1C) toward a second section (e.g., section152Q) of the waveguide.

At block 506, method 500 involves guiding, inside the second section,the light in a second direction (e.g., parallel to the y-axis in FIG.1C) different than the first direction toward a third section (e.g.,section 152R) of the waveguide.

At block 508, method 500 involves guiding, inside the third section, thelight in a third direction (e.g., parallel to the x-axis in FIG. 1C)different than the second direction.

IV. CONCLUSION

The above detailed description describes various features and functionsof the disclosed systems, devices, and methods with reference to theaccompanying figures. While various aspects and embodiments have beendisclosed herein, other aspects and embodiments will be apparent. Thevarious aspects and embodiments disclosed herein are for purposes ofillustration only and are not intended to be limiting, with the truescope being indicated by the following claims.

What is claimed:
 1. A light detection and ranging (LIDAR) devicecomprising: a substrate; a waveguide disposed on the substrate, whereinthe waveguide comprises an input end, a first section, a second section,a third section, and an output end, the first section extending betweenthe input end and the second section, the second section extendingbetween the first section and the third section, the third sectionextending between the second section and the output end, wherein thesecond section comprises a concave-shaped surface configured to focuslight into the third section of the waveguide; and a light emitterconfigured to emit light, wherein the light emitter is optically coupledto the input end of the waveguide.
 2. The LIDAR device of claim 1,wherein the second section of the waveguide further comprises a mirrorconfigured to reflect light toward the concave-shaped surface.
 3. TheLIDAR device of claim 1, wherein the first section of the waveguideextends in a first direction, wherein the second section of thewaveguide extends in a second direction different than the firstdirection, and wherein the third section of the waveguide extends in athird direction different than the second direction.
 4. The LIDAR deviceof claim 3, wherein the first direction is parallel to the thirddirection.
 5. The LIDAR device of claim 1, wherein the first section ofthe waveguide is tapered such that a cross-sectional size of the firstsection at the input end is less than the cross-sectional size of thefirst section at a given distance to the input end.
 6. The LIDAR deviceof claim 1, wherein the third section of the waveguide is tapered suchthat a cross-sectional size of the third section at the output end isless than the cross-sectional size of the third section at a givendistance to the output end.
 7. The LIDAR device of 1, wherein the firstsection of the waveguide has a first cross-sectional size, wherein thethird section of the waveguide has a third cross-sectional size, andwherein the third cross-sectional size is less than the firstcross-sectional size.
 8. The LIDAR device of claim 1, wherein the inputend includes a curved surface.
 9. The LIDAR device of claim 1, furthercomprising: an optical element disposed on the substrate, wherein theoptical element is configured to direct at least a portion of the lightemitted by the light emitter into the input end of the waveguide. 10.The LIDAR device of claim 9, wherein the optical element comprises acylindrical lens.
 11. The LIDAR device of claim 10, wherein thecylindrical lens comprises an optical fiber.
 12. The LIDAR device ofclaim 9, wherein the optical element is configured to at least partiallycollimate the light emitted by the light emitter.
 13. The LIDAR deviceof claim 9, wherein the waveguide is a first waveguide, furthercomprising a second waveguide disposed on the substrate, wherein theoptical element is further configured to direct a portion of the lightemitted by the light emitter into the second waveguide.
 14. The LIDARdevice of claim 1, wherein the waveguide is configured to guide lightfrom the input end to the output end via the first section, the secondsection, and the third section.
 15. The LIDAR device of claim 14,wherein the output end comprises a mirror, wherein the mirror isconfigured to reflect out of the waveguide at least a portion of thelight guided to the output end.
 16. A light detection and ranging(LIDAR) device comprising: a substrate; a waveguide disposed on thesubstrate, wherein the waveguide comprises an input end, a firstsection, a second section, a third section, and an output end, the firstsection extending between the input end and the second section, thesecond section extending between the first section and the thirdsection, the third section extending between the second section and theoutput end, wherein the second section comprises a concave-shapedsurface configured to focus light into the third section of thewaveguide; a light emitter configured to emit light, wherein the lightemitter is optically coupled to the input end of the waveguide; anopaque material defining a plurality of apertures, wherein the pluralityof apertures includes a first aperture optically coupled to the outputend of the waveguide; and a lens optically coupled to the plurality ofapertures.
 17. The LIDAR device of claim 16, wherein the waveguide isconfigured to guide light from the input end to the output end via thefirst section, the second section, and the third section, wherein theoutput end comprises a mirror, wherein the mirror is configured toreflect out of the waveguide and through the first aperture at least aportion of the light guided to the output end.
 18. The LIDAR device ofclaim 17, wherein the lens is configured to direct the light reflectedout of the waveguide and through the first aperture toward a scene as afirst light beam.
 19. The LIDAR device of claim 18, further comprising:a first light detector optically coupled to the first light detector,wherein the lens is configured to direct reflections of the first lightbeam by one or more objects in the scene to the first light detector viathe first aperture.
 20. The LIDAR device of claim 16, wherein thewaveguide is a first waveguide, further comprising a second waveguidedisposed on the substrate, wherein the plurality of apertures includes asecond aperture optically coupled to the second waveguide.